This is bad information.

The expression 

$expression ? $var = "foo" : $var = "bar";

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is only "# WRONG" because of operator precedence (see perlop: Operator Precedence and Associativity). Here's how it is parsed: 

$ perl -MO=Deparse,-p -e '$expression ? $var = "foo" : $var = "bar";'
(($expression ? ($var = 'foo') : $var) = 'bar');
-e syntax OK

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This is explained in perlop: Conditional Operator. Correcting the precedence with parentheses: 

$ perl -MO=Deparse,-p -e '$expression ? ($var = "foo") : ($var = "bar"
+);'
($expression ? ($var = 'foo') : ($var = 'bar'));
-e syntax OK

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I do not dispute that '$var = $expression ? "foo" : "bar";' is a better way to write '$expression ? ($var = "foo") : ($var = "bar");'. In fact, the documentation also recommends this.

Once corrected as indicated, here's how your "# WRONG" code behaves: 

#!/usr/bin/env perl -l

use strict;
use warnings;

for my $expression (0, 1) {
    my $var = '';
    $expression ? ($var = 'foo') : ($var = 'bar');
    print "\$expression = '$expression'; \$var = '$var'";
}

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Output:

$expression = '0'; $var = 'bar'
$expression = '1'; $var = 'foo'

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-- Ken

In reply to Re^2: Warning while using ternary operator by kcott
in thread Warning while using ternary operator by simonz

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